Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual é o tamanho médio da multidão da equipe da casa de Fitzroy?
 ###Tabelas: CREATE TABLE league_table (league_table_id AUTO_INCREMENT PRIMARY KEY, Club VARCHAR, Played VARCHAR, Drawn VARCHAR, Lost VARCHAR, Points for VARCHAR, Points against VARCHAR, Tries for VARCHAR, Tries against VARCHAR, Try bonus VARCHAR, Losing bonus VARCHAR, Points VARCHAR) CREATE TABLE round_21 (round_21_id AUTO_INCREMENT PRIMARY KEY, Home team VARCHAR, Home team score VARCHAR, Away team VARCHAR, Away team score VARCHAR, Venue VARCHAR, Crowd INT, Date VARCHAR) CREATE TABLE statewide (statewide_id AUTO_INCREMENT PRIMARY KEY, Date VARCHAR, State VARCHAR, George H.W. Bush VARCHAR, Bob Dole VARCHAR, Pat Robertson VARCHAR, Jack Kemp VARCHAR, Pete du Pont VARCHAR) CREATE TABLE head-to-head_records_against_other_countries (head-to-head_records_against_other_countries_id AUTO_INCREMENT PRIMARY KEY, Games INT, Wins INT, Draws INT, Losses INT, Goals For INT, Goals Against INT, Goal Differential VARCHAR) CREATE TABLE largest_cities (largest_cities_id AUTO_INCREMENT PRIMARY KEY, City proper VARCHAR, Population City limits in millions INT, Density per km² INT, Urban area VARCHAR, Population Urban area in millions INT, Metro area VARCHAR, Population Metro area in millions VARCHAR)  
SELECT AVG Crowd FROM round_21 WHERE Home team = fitzroy